IMHO "this seems to be building up" in the US is a bit of an overstatement.

Mandami, AOC, and Sanders are the laughing stock of much of the electorate in the US. They are fairly popular in progressive population centers but not elsewhere. There have been activists promoting much the same ideas for my entire life (and I'm not young!) and they rarely if ever get national traction.

The "silent majority" in the US is just that - they don't make the news because they, in most cases, don't go out and protest and engage in battles with law enforcement. They have jobs, go to work, go home to their families, and vote - but they rarely are seen in the news any more than the fact the sun came up in the East and set in the West yesterday is "newsworthy" enough to be promoted in the media. "If it bleeds, it leads" is the criteria for being newsworthy.